Gerotor device with gear drive for commutator valve

ABSTRACT

Hydraulic apparatus comprising a rotor forming a gerotor portion, a commutator valve and a planetary gear mechanism having a speed-up function of the ratio of any times as many as the number of teeth of the rotor through which mechanism said gyrotor and the commutator valve are associated with each other, wherein the rotation of the commutator valve is speeded up any times as many as the number of the teeth of the rotor with respect to that of the rotor and at the same time the direction of the rotation is changed into the opposite direction thereof, whereby the change-over portion of the commutator valve may simply be divided into two high and low pressure portions in order to make simple the structure of the gerotor type pump or the commutator valve in a motor and smooth the operation thereof.

[ 1 Dec. 10, 1974 1 1 GEROTOR DEVICE WITH GEAR DRIVE FOR COMMUTATOR VALVE [75] lnventorsz Fumio Ogasahara, Matsudo; Seiji Komamura; Katsukuni Kabuto, both of Tokyo, all of Japan [73] Assignee: Kayabakogyokabushikikaisha,

Tokyo, Japan [22] Filed: Nov. 3, 1972 [21] Appl. No.: 303,506

[52] US. Cl. 418/61 B, 137/625.2l, 180/792 R [51] Int. Cl F01: 1/02, F04c l/02, B62d 5/00 [58] Field of Search 418/61; l37/625.21, 625.24;

ISO/79.2 R; 60/384 3,452,543 7/1969 Goff et a1 418/61 Primary Examiner-John J. Vrablik Attorney, Agent, or Firm-Saul Jecies [57] ABSTRACT Hydraulic apparatus comprising a rotor forming a gerotor portion,'a commutator valve and a planetary gear mechanism having a speed-up function of the ratio of any times as many as the number of teeth of the rotor through which mechanism said gyrotor and the commutator valve are associated with each other, wherein the rotation of the commutator valve is speeded up any times as many as the number of the teeth of the rotor with respect to that of the rotor and at the same time the direction of the rotation is changed into the opposite direction thereof, whereby the change-over portion of the commutator valve may simply be divided into two high and low pressure portions in order to make simple the structure'of the gerotor type pump or the commutator valve in a motor and smooth the operation thereof.

4 Claims, 14 Drawing Figures PATENTEU DEC 1 0 I974 SHEET 10F 8 FIG..!

PATENIELEEBIOIQM .3'.a53.435

SHEET 2 BF 8 PATENTED DEC 1 01974 SHEEI 5 BF 8 CNN QQN NwN GEROTOR DEVICE WITH GEAR DRIVE FOR COMMUTATOR VALVE BACKGROUND OF THE INVENTION This invention relates to a so called gerotor type pump or a motor, or a hydraulic apparatus including it, in which a stator has one more tooth than the number of teeth of a rotor rotating therein and in which when the rotor rotates around the axis thereof, said axis rotates around the axis of another stator.

In such hydraulic apparatus, when the rotor rotates within this stator, a high pressure zone and a low pressure zone of each variable volume chamber formed therebetween move constantly and the moving direction of these high and low pressure zones becomes opposite to the rotational direction of the rotor. Therefore, during the operation of the rotor, in order to keep these high and low pressure zones communicating with respective predetermined or corresponding ports, a

very complicated commutator type valve mechanism isusually provided in a shaft connecting with the rotor. By using said valve mechanism, the momentarily or continuously moving high pressure zone and low pressure zone are always communicated with their predetermined or corresponding ports. However, it necessarily requires much labor and time, and furthermore high cost to produce such commutator valves.

For the purpose of eliminating these disadvantages, there have been proposed a commutator valve in which the revolving movement of the rotor is directly transmitted to the commutator valve so as to rotate it, whereby the structure of said commutator valve may be made remarkably simple, since the moving direction and the cycle thereof of the high and the'low pressure zones by accident often coincide with that of the axis of the rotor, or the direction of orbital movement and the cycle thereof of the rotor relative to the rotation axis of the stator. However, to rotate and drive the commutator valve directly by making good use-of the revolution of the rotor inevitably causes a disadvantageous force to be exerted on a transmission mechanism portion thereof so that the transmission mechanism does not move smoothly, which is not only undesirable for a safe operation but also causes a partially applied force to act on the commutator valve, resulting in wearing it partially.

SUMMARY OF THE INVENTION The object of the present invention is to improve such type of hydraulic apparatus, that is to say, to eliminate the above mentioned problems of the prior art and to provide an improved gerotor type hydraulic apparatus including a new valve transmission mechanism havinga simple structure and being able to be produced at low cost. The special feature of the invention resides in that the shaft connected to the rotor side and the commutator valve are associated with each other through a planetary gear mechanism, by which mechanism the rotational movement of the rotor is speeded up as many times as many as the number of teeth thereof and at the same time the rotating direction thereof is inverted and it is transmitted to the commutator valve, whereby the rotating direction of the commutator valve and the cycle thereof may be coincided with the moving direction of the axis of the rotor and the cycle thereof with respect to the rotationaxis of the stator, in other words,

the moving direction of the axis of the rotor and the cycle thereof of the high and the low pressure zones, so as to facilitate the smooth transmission of the movement between the rotor and the commutator valve and make the structure of the commutator valve itself simple.

Other objects and advantages of this invention will become apparent when reference is made to the following description considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section front view illustrating an embodiment of a gerotor type hydraulic pump motor in accordance with the present invention;

FIGS. 2, 3, 4 and 5 show longitudinal side views respectively taken along line 2 2, line 3- 3, line 4 4 and line 5 5 of FIG. 1;

FIG. 6 is a partially transversal plan view similarly taken along line 6 6 of FIG. 1;

FIGS. 7A and 7B show a commutator valve itself, FIG. 7A showing one example thereof and FIG. 78 showing the other one; I

FIG. 8 is a longitudinal front view showing an example in which the present invention is applied to a valve mechanism portion for a hydraulic power steering apparatus including a gerotor type metering pump;

FIG. 9 is a transversal plan view taken along line 9 9 of FIG. 8; g I

FIGS. 10 and 11 are longitudinal side views similarly respectively taken along line 10 10 and line 11 11 of FIG. 8;

FIG. 12 is a longitudinal front view showing another example in which the present invention is applied to a valve mechanism portion for a hydraulic type power steering apparatus including a gerotor type metering pump similarly to FIG. 8; and

FIG. 13 is a transversal plan view taken along line 13 13 of FIG. 2.

DETAILED EXPLANATION OF THE PREFERRED EMBODIMENT FIG. 1 shows a longitudinal elevation view of an embodiment of a gerotor type hydraulic pressure pump motor 20 in accordance with the present invention. This motor comprises a gyrotor part or portion 21 which is usually of cylindrical shape, a similarly cylindrical shaped valve mechanism 22, and a transmission mechanism part or portion 23. The gyrotor portion, the transmission mechanism part and the valve mechanism interposed therebetweenare integrally assembled by axially aligning them with bolts 24 and 25.

The gerotor portion 21, as shown in FIG. 2, consists of a' stator 27 having suitable number of inner teeth 26 and a rotor 29 having outer teeth 28 which are one less in number than the teeth 26 of the-stator, the rotor 29 being eccentrically disposed in a center chamber or cavity of the stator 27. The stator 27 and the rotor 29 are supported respectively at one side thereof by a distributing board 31 having a through hole 30 for operating fluid supply and discharge and at the other side thereof by a partition board 33. After the stator 27, the distributing board 31 and the partition board 32 are covered with a cover 33, said three members and the cover 33 are secured against the valve mechanism portion 22. The rotor 29, as well known, moves on a predetermined orbit in the stator 27 by the engaging operation of the inner teeth 26 and the outer teeth 28 together with the rotating movement of the rotor 29. When the rotor moves on the orbit, the outer teeth 28 thereof are sealingly engaged by the inner teeth 26 to form variable volume chambers 34 repeating expansion and contraction therebetween. Therefore, if the through hole 30 in the distributing board 31 is opened at the portion near to the bottom of these variable volume chambers 34, that is to say, the portion near to the bottom of each inner tooth 26 in the stator 27, the fluid can be supplied through hole 30 to, and can also be discharged, from the variable chamber.

FIG. 2 shows an eccentric axis of the rotor 29, unexpectedly coinciding with a vertical center axis of the stator 27 but this condition is not limitative. When the rotor begins to rotate from any condition thereof including the above mentioned condition towards the direction of either right or left, the rotor 29 moves on the orbit opposite to that of the stator 27 while it rotates within the stator 27. Now, in the position of FIG' 2, assuming that the rotor 29 is rotating counterclockwise and moves on the orbit clockwise, the variable volume chamber 34 occupying the right side from the eccentric axis will expand, while on the other hand, the variable chamber 34 on the left side will contract.

Accordingly, if the apparatus in accordance with the present invention is employed as a pump, fluid is absorbed in the right side expanding variable volume chamber 34 and exhausted from the left side contracting variable volume chamber under pressure. When the apparatus mentioned above is used as a motor, fluid under pressure is supplied to the right side expanding variable volume chamber 34 and discharged from the left contracting variable volume chamber 34.

As is apparent from these descriptions, the relation of a high pressure zone and a low pressure zonein each variable volume chamber 34 is interchanged between the case where the apparatus is used as a pump and where it is used as a motor. In any case, these high and low pressure zones respectively are always disposed on opposite sides of the eccentric axis which functions as the border thereof.

Apparently, this means that during the operation of the apparatus, the high and the low pressure zones of each variable volume chamber move towards the same direction and in the same cycle as the orbital motion of the rotor 29.

The valve mechanism portion 22 is disposed in contact with the distributing board 31 of said gerotor portion 21. This valve mechanism portion 22 comprises a casing 35 forming the exterior thereof and a commutator valve 36 rotatably accommodated therein. The casing 35 includes ports 37 and 38 for fluid supply and discharge and in the center is provided with a through hole 39 coaxial with the axis of the stator 27 in the gerotor portion 21, one end of the through hole being formed to become a reduced diameter portion 40 so as to create a shoulder portion 41. The axial movement of the commutator valve 36 is controlled by end faces of this shoulder portion 41 and disposed so as to slidably contact and rotate on these end faces and an inner surface of the through hole 39. This commutator valve 36 permits successively changing over the communication of each variable volume chamber 34 in the gerotor portion 21, via the through hole 30 formed in the distributing board 31, with the ports 37 and 38 for fluid supply and discharge provided in the side of the casing 35,

under a fixed timing. Furthermore, the commutator valve 36 enables each of the momentarily changing high and the low pressure zones of the variable volume chamber 34 to keep communicating with the predetermined port 37 or 38, whereby said operation of pump or motor may be continued. The detailed structure of this commutator valve 36 will be fully pointed out hereinbelow.

A casing 42 of a transmission mechanism part 23 which is located in contact with the valve mechanism portion 22 comprises a bored hole 43 which is coaxial with an axis ofthe stator 27 in the gyrotor portion 21, namely the axis of the through hole 39 of the casing 35 in the valve mechanism portion 22. A shaft 44 placed through the casing 42 and the commutator valve 36 in the valve mechanism 22 is rotatably disposed along the axis thereof, and one end of the shaft 44 is fitted into a large diameter portion 46 of a center hole 45 bored in the distributing board 31 in the gyrotor portion 21.

The other end is formed with a small diameter portion 47, and a shoulder portion 48 formed between the large and the small diameter portion is abutted against the casing 42 so that the axial movement of the shaft 44 can be prevented by these members. The small diameter portion 47 projects outward from the casing 42, and to the portion 47 is applied input when the apparatus of the present invention is used as a pump, or from it is taken the output when the apparatus is used as a motor.

In the bored hole 43 of the casing 42 is contained a two-step planetary gear mechanism. The first-step planetary gear 49 has a shaft supported with respect to a supporting member 51 secured to the shaft 44 by a screw and moves on a track around the shaft 44 in conjunction with the rotation thereof. This planetary gear 49 engages with an internal gear 53 provided in the side of the casing 42 while engaging with outer tooth portion 55 of an internal gear 54.

The second planetary gear 56 has a shaft 57 supported with respect to the casing 35 of the valve mechanism portion 22 and also engages with an inner tooth portion 58 of said internal gear 54 while engaging with a gear part 59 formed in a base end of the commutator valve 36 whereby the rotation movement of the shaft 44 speeded up in a fixed ratio may be transferred to the commutator valve 36.

In the rotor 29 of the shaft 44, center holes 60 and 61 are provided. Over these center holes 60 and 61 and the center hole 45 of the distributing board 31 is placed a counter or intermediate shaft 62. The ends of the intermediateor counter shafthave splines 63 and 64, respectively, one of which splines (63) engaging with the same number of teeth of spline .65 bored in the center hole 61 adjacent the rotor 29 and the other of which 64 similarly mating or engaging with the same number of teeth or spline 66 bored or formed in the center hole 60 of the shaft 44.

As pointed out earlier, the rotor 29 in the gyrotor 21 is disposed, eccentrically with respect to the stator 27, on the other hand, the shaft 44 is located with respect to said stator 27.

Thus, the intermediate shaft 62 situated within each center hole 60 and 61 ordinarily is inclined and the left end of the intermediate shaft 62 performs a rotational or orbital movement in common with that of the rotor 29 while the right end thereof carries out a simple rotadiate shaft 62 to the rotor 29 of the gerotor portion 21 or through the planetary mechanism to the commutator valve 36, so that the rotor 29 performs a rotational movement in common with the shaft 44, moving on the orbit along the stator while the commutator valve 36 performs a rotational movement in a direction opposite to that of the rotor, which rotational movement is being speeded up according to the fixed ratio relative to the rotation of the shaft 44. When the apparatus is used as a motor, in contrast with the above case, the rotational movement of the rotor 29 only is transmitted through the intermediate shaft 62 towards the shaft 44 from which it is transmitted through the planetary gear mechanism, the direction of rotation of which is opposite to that of the rotor, which is speeded up under the fixed ratio with respect to the commutator valve 36. The commutator valve 36 rotatably accommodated in the casing 35 of the valve mechanism portion, as well shown in FIG, 7, is provided with an annular projection 67 on a plane of said valve adjacent the distributing board 31 with a diametrically outward extending projection 68 which is symmetrical to the projection 67, and also withtwo diametrically and symmetrically disposed cavities 69 and 70 formed by these projections. A projection 67a which creates these cavities 69 and 70 may be shaped as illustrated in FIG. 7. On the circumferential surface of the commutator valve 36 are bored two axially spaced annular grooves 71 and 72 which are opposed to and communicate with the ports for fluid supply and discharge 37 and 38 located adjacent the casing 35.

Within the commutator valve 35 are bored two passages 7.3 and 74, through one of which are communicated the port 37 and the annular groove 71 with the cavity 69, and through the other of which are communicated the port 38 and the annular groove 72 with the cavity 70.

As is well known every time the rotor 29 having n teeth rotates in the fixed stator 27 by (360/11) degrees centering the axis of itself, the gyrotor portion 21 circulates around the orbit in the opposite direction to the rotor 29 centering the axis of the stator 27. It is apparent from the above description that during the operations'of said rotor the high and lower pressure zones of each variable volume chamber 34 created between said stator 27 and said rotor 29 move towards or in the same direction as the orbital movement of the rotor 29, and in the same cycle as said rotor. This means that if the rotational movement of the rotor is speeded up by n times and the direction thereof is made opposite, which factors are transmitted to the commutator valve 36, the rotational direction and thecycle of the commutator valve 36 coincides with the moving direction and the cycle of the high and low pressure zones of each variable volume chamber 34 in the gyrotor portion 21. Therefore, in the case of the rotor 29 having six outer teeth 28, as in the embodiments illustrated in FIGS. 1 through 7, the movement of the shaft 44 rotating together with the rotor 29 is speeded up by six times by the planetary gear mechanism and the rotational direc tion thereof is reversed which, factors are transmitted to the commutator valve 36, whereby during the operation the cavities 69 and 70 can always be operated correspondingly to each of the high and low pressure zones.

Thus, it will be understood that the apparatus in question may operate as a pump by communicating one of the ports 37 or 38 with a fluid pressure source in order to rotate the shaft 44, and as a motor by communicating one of the ports 37 or 38 with the fluid pressure source and the other port 38 or 37 with a fluid return side. Therefore, this apparatus according to the present invention permits obtaining the desired simple structure of the commutator valve 36 and the smooth operation thereof.

FIGS. 8 and 9 show a valve mechanism 200 for a hydraulic power steering apparatus combining the above mentioned gerotor type hydraulic metering pump 120 with a steering valve 220.

Since said metering pump 120 has basically almost the same construction as the hydraulic pump motor 20 we have pointedout herein above, the structure and operation thereof can be easily understood with reference to the above explanation, so that similarly operating members are designated only by adding the prefix to the original numerals and the detailed explanation of them is omitted and herein an explanation is directed only to the steering valve 220.

The steering valve 220 comprises a casing 221, a spool valve 222 and a stub shaft 223, the casing 221 being attached axially and in alignment to the metering pump by a plurality of circumferentially arranged bolts The casing 221 is provided-with a valve hole 225 axially penetrating the center portion thereof. On the circumferential surface are provided an annular groove for fluid supply 226 and pairs of annular grooves 227a and 227b, 228a and 228b, 229a and 229b, each pair being symmetrically disposed centering said groove 226. This center annular groove 226 is communicated with a hydraulic pump functioningas a source of fluid pressure through a passage for fluid supply, both annular grooves 229a and 22% being respectively commua nicated with a fluid storage tank through passages for fluid discharge 232a and 232b, and similarly the annular grooves 227a and 227b being communicated with annular grooves 171 and 172 disposed .on a circumferential surface of the commutator valve 136 towards the metering pump -through pump passages 234a and 234b. The annular grooves 228a and 228b are communicated with operative chambers 237a and 237b disposed in both sides of a power cylinder 236 through cylinder passages 235a and 235b.

The power cylinder 236 is interposed between the tie rod 239 connected to the running wheels 238 and the structural portion 240 of the vehicle, so that when said power cylinder 236 is operated the running direction of I holder 244, and the engagement of a snap ring 247 fitted in the holder 244 with an end of spool valve 222. The combination of the spool valve and the holder is positioned slidably within a valve hole 225 of said casing 221, leaving spaces 248a, 248b at both ends of the combination.

The holder- 244 has an annular groove 249 and a notch 250 on its outer surface, and a through hole 242 of said spool valve 222 is always communicated with the right space 248a through the annular groove 249 and the notch 250. A stub shaft 223 is positioned within the casing 221 and the holder 244. The reduced end 251 of the stub shaft is loosely fitted in a bored opening 175 of a shaft 144 situated at the side of the metering pump 120 and the portion adjacent to the base end of the stub shaft 223 is supported 'rotatably by a ball bearing 252 interposed between the shaft and the casing 221. The space 248a is sealed by a sealing means 253 through the bearing 252. The sealed portion of the stub shaft is extended and this extended portion is connected to the steering wheel 254. On the circumference of the intermediate portion a spline 255 is formed, which spline 255 loosely engages with the spline 176 of the shaft 144 and on the other hand tightly engages with the spline 256 of the holder 244 ((see FIGS. 10

and 11). Within the bored opening 257 formed along the axis of the stub shaft 223, a torsion bar 258 is received and the ends of the torsion bar are connected by means of pins 259, 260 respectively, to the shaft 144 and the stub shaft 223, the axes of which coincide with the torsion bar 258. Accordingly, the shaft 144 and the stub shaft 223 are connected with each other through the torsion bar 258.

According to the embodiment of FIGS. 8 and 9, the shaft 144 situated in the side of the metering pump 120 is supported by means of a ring member 261 placed securely within a valve bore 225 formed in the casing 221 of the steering valve 220. The ring member 261 presses upon the step portion 262 of the valve bore 225 formed in the casing 221, through a shim 263, and is fixed securely by a ring nut 264 positioned in the rear of the ring member 261. Furthermore, the ring member 261 is fixed rigidly by means of a collar 266 positioned in one side of the ring member and abutting a step portion 265 of the shaft 144 and a holding member 151 positioned in the other side of the ring member with a screw 150 through thrust bearings 267. The shaft 144 has a feed screw portion 268 which engages with an internal thread 269 formed on an inner surface of a left end of a holder 244. Accordingly, the spool valve 222 may be placed at a neutral position without any torsion generated in the torsion bar 258, as shown, within the valve bore 225 of the casing 221, by shifting the engaging position of the feed screw 268 and the inner thread 269 toward a direction owing to the force of the spring 271 interposed between a step portion 270 of the stub shaft 223 and the right end portion of the holder 244.

As will be apparent from the above description, unless force is applied on the steering wheel 254, the pres surized fluid delivered from a hydraulic pump 231 is returned to the tank 233 through a supply line 230, the annular groove 226, the through hole 242 of the spool valve 222, an annular groove 249 and a notch 250 of the holder 244, a right space or room 248a, an annular groove 229a, and discharging passage 232a.

When a steering force is applied to the steering wheel 254 so as to revolve the wheel clockwise or counterclockwise, the steering force will be transmitted from the stub shaft 223 to the shaft 144 through the torsion bar 258 and as a result of it a rotational force is applied to a rotor 129 of the gyrotor part 121 through an intermediate shaft 144, so as to deliver the operating liquid into a space 237a or other space 237b of the power cylinder 236 according to the direction of revolution of the steering wheel 254 and to steer the running wheels 238. Some resistance owing to the friction. produced between the running wheels and the road is applied to the steering force of the wheels 238, so that before the running wheels 238 are steered, the stub shaft 223 revolves and twists the torsion bar 258 with halting of the shaft 144 and the preceding members in order to generate some relative angular motion of the splines 176, 255 within the scope of play or clearance of them. As the holder 244 revolves together with the revolution of the stub shaft 223 through the splines 255, 256 and the inner thread 269 of the holder 244 engages with the feed screw 268 of the shaft 144, the holder 244 moves axially together with the spool valve 222 to change over the valve.

It is assumed that the steering wheel or handle 254 is revolved counterclockwise in order to change over or shift the spool valve 222 to the left. Then, the flow direction of pressurized liquid delivered from the hydraulic pump 231 to the tank 233 is changed over to deliver the liquid into the expansion side of variable volume chamber 134 in the gyrotor part 121 through a delivery passage 230, an annular groove 226, the annular groove 241a of the spool valve 222, the annular groove 227a of the casing 221, a pumping passage 234a, the annular groove 171 of the commutator valve 136, a passage 173, a cavity 169, and the through hole of the distributing board 131, respectively. As a result of it, a revolutional motion having revoluting direction of the stub shaft 223 is applied to the rotor 129 and the revolutional motion is fed back from the intermediate shaft 162 to the shaft 144 in order to control the volume of the pressurized liquid which is forced out of the contraction-side variable chamber 134 of the gerotor part 121,.according to the angular motion of the steering wheel 254 or, in other words, to meter the volume of the pressurized liquid passing through the gerotor part 121 corresponding to the angular motion of the steering wheel 254. The pressurized liquid is simultaneously delivered to the space 237b of the base endside of the power cylinder 236 through the through hole 130 of the distributing board 131, the cavity of the commutator valve 136, passage 174, an annular groove 172, the pumping passage 234b, an annular groove 227b, the annular groove 241b of the spool valve 222, the annular groove 228b of the casing 221, and the line 2351:.

On the other hand, operating liquid within the opposite space 237a is pressed back to the tank 233 through the cylinder passage 235a, an annular groove 228a, a right space and room 248a, an annular groove 229a, and a discharging passage 2320. Therefore, the power cylinder 236 extends corresponding to the angular motion or position of the steering wheels 254 in order to steer the running wheel 238 to the left by means of the tierod 239.

In case the steering handle 254 is turned to the right or clockwise and the spool valve 222 is changed over to the right, the pressurized liquid delivered from the hydraulic pump 231 is transmitted to the variable volume space 134 of the gyrotor part 121 through a feed passage 230, annular grooves 226, 241b and 227b, a pumping passage 234b, an annular groove 172, a passage 174, a cavity 170, and a passage 130. Simultaneously, the rotor 129 turns in the direction opposite to the former one, that is to say, the rotor 129 turns along the same direction as the stub shaft 223 in order to meter the pressure fluid passing along the rotor according to the angular motion of the'steering wheel, and the fluid is fed to the operating space 237a at the forward end of the power cylinder 236 through a through hole 130, a cavity 169, a passage 173, an annular groove 171, a pumping passage 234a, annular grooves 227a, 241a and 228a, and a cylinder passage 235a. Simultaneously the operating liquid within the operating space 237!) of the base end is pressed back into the tank 233 through the cylinder passage 235b, annular passage 228b, the left space 248b, an annular groove 229b, and a discharging passage 232b, to cause the shortening operation of the power cylinder 236 corresponding to the angular movement of the steering wheel 254 in order to steer or turn the running wheel toward the right by means of the tierod 239.

In this way, if the steering wheel or handle 2S4 stops its rightward or leftward angular motion at a desirable angular position in each case, the delay in phase of the revolution movement of the shaft 144 to that 01 the stub shaft 223 will not be generated and the spool valve 222 will be returned to the neutral position shown by the cooperation of the feed screw 168 and the inner thread 269, and the pressurized liquid delivered from the hydraulic pump 231 will be caused to flow back to the tank 233, and at the same time both operating spaces 237a and 237b within the power cylinder 236 will be sealed or blocked from the position of the annular grooves 228a and 228b in order to sustain the running wheels 238 at the steered position at that moment.

According to the mechanism of this invention shown in FIGS. 8 and 9, it will be apparent that the steering handle 254 can be steered or turned in a desired direction by using a pressurized liquid correspondingly to the angular position of the handle or wheel 254.

The check valve 272 as shown is interposed between a feed passage 230 and the return line .to the tank 233; accordingly, in case the hydraulic pump 231 is not operative for some reason, the steering operation can be carried out manually.

This is because the operation of the handle causes the twisting motion of the torsion bar 258 owing to the stub shafts operation, so that the spline 255 of the stub shaft 223 is abutted against a side wall of a tooth of the spline 176 in the side of the shaft 144. Therefore, the position of the spool valve 222 is changed and subsequently the revolutional operation of the stub shaft 223 is transferred to the rotor 129 of the gerotor part 121 through the splines 255 and 176, a shaft 144, and an intermediate shaft 162, so that the gyrotor part operates as a hand pump to absorb the operating liquid at the return side through said check valve 272 and to feed the pressurized liquid toward the power cylinder 236.

In the embodiments described above, includingthat of FIG. 1, a transmission mechanism part or portion 123 is positioned at the projecting side of the shaft 144 so that if a large speed-up ratio is is desired to be obtained by means of a one-step planetary gear mechanism, the outside diameter of the mechanism would become very large. Therefore, a two-step planetary gear mechanism is adopted in order to obtain a desired speed up ratio in the embodiments shown in FIGS. 1 through 11. On the contrary, in the embodiments shown in FIGS. 12 and 13, the desired speed-up ratio is obtained by replacing the transmission mechanism part 123a with the gerotor part 1210 and using a onestep planetary gear without having to enlarge the outer diameter of the parts.

The embodiments shown in FIGS. 12 and 13 will now be described in more detail. In these embodiments, the gerotor part 121a is situated at the right of a valve mechanism part 122a and the transmission mechanism part 1230 is positioned at the left of the'valve mechanism part, in order to form a metering pump a which is placed or put on a steering valve 220 through the gerotor part 121a and a partition board 132a. They are fastened or combined integrally to construct a valve mechanism 200a of a hydraulic power steering apparatus. The steering valve 220is identical with those of the embodiments shown in FIGS. 8 through 11 so that there is no necessity to explain about the steering valve 220 herein.

The gerotor part 1210, similarly to those of the embodiments described above, comprises a stator 127a and a rotor 129a the number of teeth of which is one smaller than that of the stator 127a, and the rotor 129a is placed eccentrically in the stator 127a. An intermediate shaft 162a is inserted through the center holes a and 161a of the rotor 129a and the shaft 144a, and the rotational movement thereof can be transmitted between the rotor 129a and the shaft 144a by inserting the pins 163a and 164a attached to the ends of the intermediate shaft 162a into axial grooves 165a and 166a formed on the center holes 160a and 161a of the rotor 129a and the shaft 144a. In the embodiment shown in FIGS. 8 and 9, a support member 151 supporting the primary planetary gear 149 situated within the transmission mechanism part 123 engages with a shaft 144a in order to secure an annular member 261 into its proper place. On the contrary, according to the embodiment of FIGS. 12 and 13, the annular member 261 is secured in the position between the shaft 144a and a separate nut 151a.

The valve mechanismpart 1220 of the embodiment shown in FIGS. 12 and 13 has two cavities 169a and 5 170a separated from each other and formed on a side of the part, and coaxial ring grooves 171a and 172a formed on the other side of the part, in order to make the valve mechanism part 122a thin and to shortenthe I whole length of the apparatus. In the embodiment of FIGS. 12 and 13, a commutator valve 136a is constituted by communicating these annular grooves 171a and 172a with the cavities 169a and 170a, respectively, through passages 173a and 174a, and the commutator valve 136a is received rotatablywithin a through hole 139a of a casing 135a/A side of the commutator valve 136a is applied to the gerotor part 121a through a distributing board 131a. Variable volume chambers 134a within the gerotor part 1210 are communicated with two cavities 169a and 170a through a through hole 130a formed in the distributing board 131a. A partition board 178a having through holes 177a and 177b and a spacer having two passages 179a and 17% are applied to the other side of the commutator valve 136a, and the annular grooves 171a and 172a which are arranged coaxially of the commutator valve 136a arecommunicated to the pump passages 234a and 234b through the through holes 177a and 177b of the partition board 178a and the passages 179a and 17% of the spacer 180a.

The transmission mechanism part 123a consists of a plurality of planetary gears 149a supported on the fixed supporting member 181a by a shaft 152a, and rotatable inner gears 153a engaging with the planetary gears 149a. These planetary gears 149a and the rotatable inner gears 153a are received in a bored hole 143a of the casing 142a secured to the valve mechanism part 122a through the fixed supporting member 181a. The planetary gears 149a engage with the geared portion 183a formed on the end of a transmission member 182a which is situated through the commutator valve 136a, a partition board 178a, a spacer 180a and the fixed supporting member 181a and, also, the base end of the transmission member 182a is connected with the commutator valve 136a by the key l84a'so as to transmit the revolutional motion of the planetary gear 149a from the transmission member 182a to the commutator valve 136a through a key 184a. Within the center hole 185a of the transmission member 1820, there is a second intermediate shaft 186a the left end of which is connected to the inner gear 153a through a pin 183a and the right end thereof extends through the distributing board 131a into the gyrotor part 121a. The right end of the second intermediate shaft 186a is connected to the connecting member 189a through a pin 190a, which connecting member 189a is situated and secured in the central hole 161a of the rotor 129a by means of cutting groove 165a and a key 188a. In this way, the intermediate shaft 186a is, together with the other intermediate shaft 162a and a rotor 129a of the gyrotor part 121a, situated within the stator 127a which is placed in an eccentric position, and the inner gear 153a and the shaft 1440 are placed coaxially with the stator 127a, so that the rotor 129a, the inner gear 153a and the shaft 144a are respectively connected with the intermediate shafts 186a and 162a through universal joints.

Thus, the rotational motion of the shaft 144a is transmitted to the rotor 129a of the gerotor part 121a through the intermediate shaft 162a and also its speed is increased through the intermediate shaft 186a, the inner gear 153a, the planetary gear 149a and a transmission member 182a. Then, the direction of the rotational movement is reversed this is transmitted to the commutator valve 136a. Accordingly, the diameter of the geared portion 183a of the transmission member 182a may be exceedingly reduced in comparison with the diameter of the inner gear 153a, so that it is possiand low pressure zones of each variable volume chamber 134a in the gyrotor part 121a. The operation of the embodiments shown in FIGS. 12 and 13 will be easily understood in view of the explanation of the embodiments of FIGS. 8 and 9.

While the invention has been described in considerable detail, we do not wish to be limited to the particular embodiments shown and described, and it is our intention to cover hereby all novel adaptations, modifications, and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

What is claimed is:

1. In a hydraulic apparatus, a combination comprising a housing having a fluid supply port and a fluid discharge port;

a gerotor in said housing and including a stator, and

a rotor which is rotatable relative to said stator and has a low-pressure zone and a high-pressure zone;

a commutator valve rotatably received in said housing and having two cavities indexed to face said high-pressure and low-pressure zone and being in communication with said fluid supply port and said fluid discharge port, respectively;

a main shaft extending through and defining an axis of rotation for said commutator valve;

an intermediate shaft having one end connected with said main shaft and another end connected with said rotor for rotation with the same in a first direction and at a first speed; and

gear means connected with said main shaft and said commutator valve and operative for rotating the latter in a direction opposite to said one direction and at a second speed which is greater than said first speed by a fixed ratio.

2. A combination as defined in claim 1; and further comprising a steering valve for steering the wheels of a vehicle, said steering valve having a metering pump passage side and a stub shaft and said parts being communicated with said pump passage side; and further comprising a torsion bar connected with said stub shaft and with one of said main and intermediate shafts.

3. A combination as defined in claim 1, wherein said stator has a first number of teeth, and said rotor has a second number of teeth which is smaller by one than said first number of teeth.

4. A combination as defined in claim 3, wherein said gear means rotates said commutator valve at said second speed which is greater than said first speed by a number of times which corresponds to said second number of teeth on said rotor. 

1. In a hydraulic apparatus, a combination comprising a housing having a fluid supply port and a fluid discharge port; a gerotor in said housing and including a stator, and a rotor which is rotatable relative to said stator and has a lowpressure zone and a high-pressure zone; a commutator valve rotatably received in said housing and having two cavities indexed to face said high-pressure and lowpressure zone and being in communication with said fluid supply port and said fluid discharge port, respectively; a main shaft extending through and defining an axis of rotation for said commutator valve; an intermediate shaft having one end connected with said main shaft and another end connected with said rotor for rotation with the same in a first direction and at a first speed; and gear means connected with said main shaft and said commutator valve and operative for rotating the latter in a direction opposite to said one direction and at a second speed which is greater than said first speed by a fixed ratio.
 2. A combination as defined in claim 1; and further comprising a steering valve for steering the wheels of a vehicle, said steering valve having a metering pump passage side and a stub shaft and said parts being communicated with said pump passage side; and further comprising a torsion bar connected with said stub shaft and with one of said main and intermediate shafts.
 3. A combination as defined in claim 1, wherein said stator has a first number of teeth, and said rotor has a second number of teeth which is smaller by one than said first number of teeth.
 4. A combination as defined in claim 3, wherein said gear means rotates said commutator valve at said second speed which is greater than said first speed by a number of times which corresponds to said second number of teeth on said rotor. 